Reverb and delay are arguably the most common effects used at mixdown, but because they find so many different uses in this context they can seem bewildering to musicians who are still in the process of getting to grips with the fundamentals of studio production — those setting up a home studio, perhaps, or those enrolled in a music technology course for the first time.

Part of the problem inevitably stems from the wide range of different devices available that can supply these types of effects, and from their frequently inscrutable editing parameters. There is, however, an enormous amount of information on hand to demystify such technicalities, not least in Sound On Sound's on-line article archive (see the 'Further Reading' box for some suggestions). Furthermore, the preset-led nature of many effects units these days makes it unnecessary for the beginner to delve very far into their algorithmic innards, and to be honest I think there are quicker results to be gained at the outset by working from presets, and leaving most of the effects parameters well alone!

As I see it, the more pressing difficulty when starting out is dealing with basic practical questions such as how many different effects to use, which effects to apply to which instrument, and how to decide on suitable levels. So in this article I'll be trying to eliminate some of the guesswork by suggesting a basic general-purpose approach to using reverb and delay while mixing. In the process I'll pinpoint some things to watch out for when surfing reverb presets, as well as highlighting the handful of effects parameters and techniques that make the biggest impact with the least effort.

However, I've always felt that there's only so much you can communicate in print alone when you're dealing with mixing techniques, so I've also put together a bunch of audio examples so that you can judge for yourself how useful each of my proposed methods is in practice. You can download them in MP3 or WAV format from the SOS web site at .

On the most fundamental level, both delay and reverb are about adding the characteristics of an acoustic environment, either by creating simple echoes or by simulating more complex patterns of sonic reflections. The reason these effects are usually so important at mixdown is because the individual parts in most modern multitrack projects communicate very little in the way of a common sense of space, and as such sound a bit 'dislocated', rather than seeming to belong on the same record. Obviously, synthesizers and sampled sounds often have no sense of acoustic realism to them at all, but even miked instruments are often recorded very close up, to reduce room reflections as much as possible, allowing decisions about the nature of the production's overall acoustic space to be deferred until the final mixdown.

For this reason, the primary objective of reverbs and delays is to reconnect tracks that have no inherent connection by giving them some shared acoustic characteristics, and it's this task that's the subject of the article at hand. Naturally, there are creative applications of reverbs and delays too, but these are window-dressing in most mixes (as well as being very much more a matter of personal taste), and will do your mix little good if the main edifice doesn't really cohere properly.

Because the underlying aim is to give the separate tracks something in common, it makes sense to set up your plug-ins or hardware processors so that the same effect can be applied to multiple tracks at the same time. Whether you're using a hardware or a software mixer, the manner of doing this is pretty much the same. First of all you set up the output of your effects processor to feed a spare stereo mixer channel; then you set up a separate mix of your tracks specifically for the effects processor and send it to the unit's inputs, whereupon the effected signal feeds back into the mix. By changing the levels of the different tracks in the send mix, you determine how much of the effect is added to each track.

In hardware systems, the mixer will have auxiliary send controls which allow you to create a number of independent effects-send mixes, each mix appearing on a separate output socket. By connecting different effects units to the mixer's different auxiliary-send outputs, you can drive several independent effects at once, assuming that you have enough free mixer inputs through which to return their outputs. In software, a separate mixer channel usually needs to be created to hold the effect plug-in, whereupon auxiliary sends can be created on each relevant mixer channel to feed it. (This is exactly the kind of setup I used in Cockos Reaper to create my audio examples, using a section of an otherwise dry multitrack project.)

Irrespective of which kind of system you work in, though, there are two important things that you need to bear in mind if you're going to ensure that this kind of effect configuration (usually called a 'send effect' or 'effect loop') works properly. The first thing is that you need to make sure the processors or plug-ins you're using only output effects, not a mix of processed and unprocessed signals, otherwise changing any auxiliary send level will also have an impact...